MONTEREY — On Thursday, a day after the 29 year anniversary of the Loma Prieta earthquake, close to 105,000 Monterey County residents practiced how to take cover during the annual Great Shake Out, a statewide drill to encourage earthquake preparedness.

But what if that day in 1989 would have unfolded differently? What if seconds before the San Andreas fault unloaded, you received an alert that estimated when shaking would start, and just how intense that shaking would be, in your exact location?

New technology developed by the U.S. Geological Survey and partners could warn the public seconds to tens of seconds before an earthquake hits, giving enough time to drop, cover, and hold on.

The tech would also notify operators to stop car, bus, and train traffic, shut off volatile utility lines, and even surgeries. So far, ShakeAlert has been implemented by organizations such as Bay Area Rapid Transit, Lawrence Livermore National Laboratory, Pacific Gas & Electric Co., Chevron, UC Berkeley Police Department, and Menlo Park Fire Department.

Delivering the message

USGS ultimately wants to reach the public, through an app, or an emergency message delivery system similar to Amber Alert, says Bob deGroot, a USGS staff scientist who works on the ShakeAlert project. On this next step deGroot says, “Cell companies have to get involved. It would be their responsibility to take whatever message is being made available and deliver it to subscriber.”

Currently, USGS is collaborating with the city of Los Angeles and AT&T to bring ShakeAlertLA, an app, to residents there.

But, deGroot is hesitant to say that ShakeAlert is a silver bullet to the dangers a high magnitude earthquake presents.

“It buys you some time, so you have an opportunity to take whatever protective action you can,” deGroot said. “It’s a good tool, but it’s not going to solve everything.”

An earthquake alert system would aim to give people a warning seconds before an earthquake hit. (Vern Fisher – Monterey Herald)

When an earthquake occurs, two separate types of seismic waves deliver energy to the surrounding areas. P-waves will always be the first wave to arrive at any location from the epicenter of the quake, Heather Shaddox, UC Santa Cruz seismology graduate researcher explained.

The waves move like a slinky, she says, “If you’re walking side to side with your slinky, doing a push pull motion, that’s how p-waves travel.” But s-waves, have two distinct movement components; up and down, vertically, and side to side, horizontally. The two styles of s-wave shaking hit at once, often causing more damage than p-waves.

ShakeAlert sensors strategically placed up and down California, including Monterey, Oregon, and Washington pick up initial p-wave movements. Then that data is sent to computer systems that analyze where the earthquake originated, when it happened, and how strong the quake will be. An automated decision is then made on whether a ShakeAlert should be issued.

Within 5 seconds of the initial p-waves USGS says it can be ready to provide this crucial information for distribution to the public, using cell towers, with the help of private entities who own the towers, and can deliver the message. So far there are about 890 sensors across the west coast, but ultimately USGS and its partners plan to install 1,675.

How quickly the alert can be sent to cell phone users is still being perfected.

Location, location, location

Regardless of the ShakeAlert delivery times, in the world of earthquakes, it’s location, location location. How much destruction an earthquake inflicts depends on the hazard, and risk of a location, said Bill Godwin, California Licensed Professional Geologist who has consulted on seismic investigations and emergency response projects for dams and pipelines. “Risk means there’s a human component. If it’s a high hazard area, and urban, then it’s high risk. If there’s high hazard, but if there’s no one there to be hurt, there’s relative low risk.”

He compared Parkfield at the southern end of Monterey County and Oakland. Parkfield is the self declared earthquake capital of the world, and is situated directly next to the San Andreas Fault. But it only has a population of about 18. Oakland boosts a population of close to half a million and is an impacted urban area, and neighbors the Hayward fault.

“In a big urban environment, not the Monterey Peninsula necessarily, but in much bigger cities you’re almost trapped, and you’re around a lot of big structures. Not all those structures are seismically safe…that (shake alert) is going to be very helpful in an area where there are a lot of people, and critical facilities like pipelines, or a subway system, or where that train were to come off the tracks, it can really hurt people,” Godwin said.

Earthquake waves move uniquely depending on what type of materials they move through. “Within the greater Monterey Peninsula, in an earthquake scenario, you have two different kinds of boundaries; a more stable, shallow bedrock up in the higher areas, and liquefiable weak, soil around the perimeters around the tidal areas,” Godwin said, generalizing.

Areas around the Monterey Bay, El Estero, and where rivers meet the sea, such as Elkhorn Slough, or Carmel River Lagoon, soils are constantly being renewed, and can be easily permeated by water Godwin said. Shaddox added that, “In looser materials, like soil, shaking is stronger.”

Homes and businesses close to these watery areas at more at risk.

Bolting stuff to the wall

Even though much of the Monterey Peninsula sits on hard bedrock, taking measures to protect your home is important, Godwin says. “Most people are injured in earthquakes not by buildings falling on them but everything in their house falling on them…like up on the mantelpiece, a vase, or a big picture, or a bookcase in your office that’s not bolted to the wall. All those things are going to come down, and if you’re in that house they’re going to hit you on your head and hurt you.”

For ideas on how to be more prepared for an earthquake, read this guide developed specifically for the Central California Coast: https://bit.ly/2Cv7fL4